South Africa and Namibia are two of the most unequal countries in the world. These inequalities have very strong and persistent racial and geographic dimensions due to the legacy of colonial and apartheid segregationist policies, which today manifest themselves in large rural-urban area and racial differences in education and labour market opportunities. Spatial inequalities in both countries have encouraged rapid urbanisation despite labour market prospects being poor. As a result, numerous studies have investigated the roles of spatial location and mobility, and the role that that mobility has in alleviating poverty and inequality in the Southern African context over time. This dissertation contributes to the Southern African literature in two ways. Firstly, it identifies individual and region-level characteristics that influence migration decisions at the individual level, and at the aggregate level by analysing gross migration flows. Secondly, it contributes to a very small body of South African literature using panel data to study the dynamics of new urban household formation. The empirical evidence presented in this dissertation shows that internal migration in South Africa continues to be an age and education-selective process. Previous migration experience, as well as sending area net out-migration rates significantly increase the probability of internal migration in South Africa. These findings are robust to the inclusion of various individual and region-level controls. The study of urban informal area household formation in South Africa reveals that relative youth, marital status changes and recent migration positively affect the probability of forming a new urban informal household. The study also finds that urban informal area residents have weak labour market prospects relative to urban formal area residents, but in most respects fare as well as or better than traditional authority residents. The gravity model estimated using Namibian data shows that constituency-level factors affect migration flows in different ways, dependent on the distance traveled. The contribution of this study to the literature is the finding that studying migration flows without group disaggregation may mask differences in migrant motivations.